Does milk solution work for Powdery Mildew on Squash?

I woke up today to find white PM spots all over my sunburst (yellow) squash and cukes, and possibly my zucchini.

I was overwatering them, I'm sure. :-) The weather here has been perfect for them and they haven't been thriving. THey're in full sun from about 9 am to 5 pm and temps from 85-95.

So... I've seen differing reports about the milk solution, and none of my local nurseries know anything about it.

I've seen a lot of the older posts, right when the first few studies came out about milk, and I'm wondering what the consensus now is. Does it work? I've seen the 10% and 50% milk quoted. I've also seen that it's only for prevention and others say it works for treatment as well.

Any help?

Should I just yank them and start over from seed? (Here it'll stay hot until October, probably, so I do have a nice long growing season.)

I read a study about the use of a 10% milk solution on grapes to combat PM. The study reported the milk was as effective as chemical treatments.

Encouraged I used a 10% milk solution on everything I grew that got PM and found it offered little.

To this day though if I have soiled milk I use it on plants rather than toss it.

My opinion, based upon my experiences with milk, is that it hasn't done anything for me, but it has been tested and found effective by others. I don't know what variables control it's effectiveness. I use it if the alternative is tossing it out, but don't spend money to buy it for anti fungal use.

Actually, if you're going to spend money on something to combat powdery mildew, you might as well go with milk. It's been tested and proven to be effective against powdery mildew and even at the current high prices it's still probably less expensive than alternatives!

The fat free milk and water spray will work on Powdery Mildew on any plant. I have always mixed that spray 50/50 and found that most often the PM problem is solved with one spray, but you could mix it weaker and spray more often if that is your choice.

Thanks folks, I ended up spraying with the Organocide last night since thats what I had leftover from a citrus scale thing this spring. It's OMRI listed, just a mix of fish oil and sesame oil. Stinks to all get out. LOL

I have used the milk (approx 30%) on roses and peas and grapes and it works wonders. I will sometimes come back a few days later and do an additional spray just to take care of anything left (not really necessary...). The reason I use milk rather than anything else is that it works, but also acts as a foliar fertilizer.

This is not the source I got it from, but gives some general info on milk for PM and as a fert.

I've tried the milk solution and not found it to be effective on my squashes in coastal CA. After many years of the same problem, using supposedly PM-resistaint strains and species and various sprays, nothing has worked. I've found the PM doesn't affect the veggie, so I grow them as very short-lived and germinate new plants every 8 weeks or so.

Perhaps, those that spray less than the 50/50 mixture of fat free milk and water, what you are spraying is not enough to properly control the disease and that is why you need to repeat the spray to "control" that. Perhaps also spraying not enough to do the job will allow those spores to develop immunities to that material so it will be less effective in the future. That has happened with many of our current poisons, the target has developed immunities to the poison and it is no longer effective.

Zinnia's are my target for the milk mix and it works for me with the 50/50 mix...if I spray before I see the PM. Lets see, we've had 14 inches of rain since Memorial Day, maybe its Golden Guernsey time.

Below is a link to a scientific study into the efficacy of diluted milk in controlling powdery mildew on zucchini squash. It is the only scientific research into the use of milk in this manner that I am aware of. (It is PDF format and requires an Adobe program to open.) Notice it deals with fresh cows milk (one would presume whole milk.) I'm not sure where the fat-free idea came from but haven't seen studies that support that nor has my successful use of whole milk or 2% shown any difference in success.

The study indicates low concentrations at more frequent applications are effective while less frequent applications requires higher concentrations.

An interesting observation is that the study indicates that the rate of control can equal the success of synthetic fungicides.

Bettiol talks about using fresh milk, which in Brazil is raw, not pastureized, milk. Since few of us have access to raw milk, and the study I saw from the USDA suggested using fat free milk, this is what I have used, successfully at the 50/50 mixture to control PM. Most often one spray was all that was needed, if I sprayed when the first signs of PM appeared, but if I waited a bit that might require two or three sprays. I have not, in the many years I have used milk and water needed to spray every week. There seems to be some difference in the fat in pasturized milk versus raw milk.

Thanks for the link, Wayne. There seems to be something inherently pleasing when science reaffirms folklore.

kimmsr- I usually make two applications about 2-3 weeks apart. Not sure if I really need the second I just do it. Another difference in milk, as fat content gets lower, the calcium content gets higher in our milk. Some calcium molecules will kill mildew, maybe that is a factor-just guessing.

This is my first post ever, but I search and read the postings pretty frequently and all of your advice has been very helpful. I am new gardener too, so I have a ton of questions.

I've been 'spraying' milk/water on my squash - 3 applications over 3 days, but nothing is happening. Should I expect it to go away. My plants have it pretty badly. Does it stop them from producing? Could it be that my system for spraying is more like drizzling? Any advice would be appreciated.

embarnet- I don't believe I have ever seen it cure the powdery mildew on any of my plants. It has been effective at stopping my plants from getting PM, and once the PM was there the milk may have slowed its spread, but I've never seen the PM disappear.